We developed an analysis system for the muscle mechanics of shoulder and elbow joints. The system can calculate kinematic and dynamic data of the upper limb such as velocity, acceleration, joint force, and moment by using motion analysis data. The system also incorporates a musculoskeletal simulation system to determine muscle directions and rotational moment arms. While the forces generated by the dynamic contraction of the muscles can be obtained by combining the physiological parameters of the muscle and by using numerical calculation methods.